Determination of Sr-90 in aquatic organisms by extraction chromatography: method validation

A method is presented for the determination of Sr-90 in plankton and cod ma trices using extraction chromatography. The samples were microwave digested using closed-pressurised vessels and the Sr-90 was separated by extraction chromatography using a crown ether sorbed on an inert substrate. The separ ation yield of Sr ranged from 80 to 100%. Separation reproducibility, resin capacity and matrix effect were also investigated. The maximum resin capac ity was 8.76 mg of Sr/g of resin. The same resin could be used more than te n times without decrease of performance. Except Ba, which eluted together w ith Sr, none of the elements studied interfered with the separation of Sr s ince practically all were washed out before the elution step. A method usin g 8 M HNO3 as washing agent, before the Sr elution with 0.05 M HNO3, is pro posed to remove Ba completely. The separation method was checked with BCR C RM 414 Plankton and BCR CRM 422. Cod Muscle spiked with Sr-90. (C) 2000 Els evier Science B.V. All rights reserved.